What are the current big challenges in natural language processing and understanding?
According to a nice article by Sebastian Ruder https://ruder.io/4-biggest-open-problems-in-nlp/ based on answers from top NLP researchers https://docs.google.com/document/d/18NoNdArdzDLJFQGBMVMsQ-iLOowP1XXDaSVRmYN0IyM/edit


Natural language understanding
NLP for low-resource scenarios
Reasoning about large or multiple documents
Datasets, problems, and evaluation


I recommend having a look at the article. More details in the slides https://drive.google.com/file/d/15ehMIJ7wY9A7RSmyJPNmrBMuC7se0PMP/view